Adapted from Simon Wrisberg’s historical book, Danish Beer 1850–1950, here’s a traditional recipe for gammeltøl.
It’s a distillation of several 19th century recipes, translated for modern kit. “The fermentation was normally done in barrels with top-fermenting yeast,” Wrisberg says. “If the barrel was filled with wort, the surplus of yeast would run out of the bunghole [and] was used for baking.”
For more on this near-forgotten tradition, see Brewing Gammeltøl, Denmark’s Strong and Smoky Harvest-Time Farmhouse Ale.